It is well known that the human body is equipped a number of sypmathetic centers, or thermostats, which help control its internal temperature. Specifically, the hands, feet, forehead, and ears serve to regulate the body temperature. When one or all of these more highly exposed areas becomes cold, the human body loses internal heat, causing the remainder of the body to become cold.
It is well known that blood flow through the body helps to maintain the proper internal temperature, and when blood flow slows, that temperature declines. Further, it is well known that during sedentary activities such as hunting from a stand or watching outdoor sporting events, the blood flow to the extremities decreases as compared to non-sedentary activities. In cold weather, it is well known that this decrease in blood flow will cause the extremities, especially the feet and hands, to become cold. In extreme weather and extended exposure, the body may suffer sever harm due to frost bite, hypothermia, or other similar physical disabilities.
The body generates heat to the skin by heating blood within the internal organs of the body and pumping the heated blood toward the skin. When the blood flow is decreased, the heat transferred to the skin is proportionally decreased. The blood vessels delivering the heated blood penetrate the subcutaneous insulator tissues and the blood is distributed in the subpapillary portions of the skin.
Immediately beneath the skin is a continuous plexus which is supplied in only the most exposed areas of the body, those being the hands, feet, forehead, and ears. The blood is delivered through direct arteriovenous shunts from the arterioles to the veins. The rate of blood flow to the venous plexus is a determining factor in the conduction of heat from the internal organs to the skin.
The rate of flow to the venous plexus is largely controlled by the vasoconstriction of the arterioles, which is largely controlled by the sympathetic nervous system, the centers of which are those areas being most exposed--the hands, feet, forehead, and ears, as previously described. As the sympathetic centers of the posterior hypothalamus are stimulated, as with the introduction of cold or warm air, the constriction of the arterioles is accordingly increased or decreased, substantially reducing flow of blood to the skin. Cooling the sympathetic centers causes the hypothalamus to constrict the venous plexus, thereby reducing the blood flow, while warming the sympathetic centers causes a dilation of the venous plexus and an increase in blood flow.
Several methods are currently used to help prevent the adverse effects of cold weather. For example, materials have been developed to more efficiently retain the heat produced by the body. These types of materials act as insulation, but serve only to retain heat, and not to produce heat. These materials are used in boots, gloves, and other related articles of clothing for retaining the heat generated by the body proximate the hands and feet.
It is well known that a layer of air surrounding the human body serves as an insulator. The internal body temperature is constantly adjusting to the temperature of the surrounding air such that as the surrounding air cools, the body heat is dissipated. Further, as the body is cooled in this manner, the blood veins in the proximate area constrict, thereby slowing the flow of blood to that area, which also causes a further cooling of the body.
As mentioned, sedentary activity reduces the amount of heat produced by a person's body. The use of insulators to prevent the escape of heat from a person's body during sedentary activity, though helpful, does not serve to maintain the person's body temperature. The insulators merely slow down the decrease of the person's body temperature.
It is desired that a means be provided whereby the body temperature of a user may be elevated by heating the air surrounding a selected body part, thereby avoiding the adverse effects of continued exposure to cold weather during sedentary activities. When used to protect the hands of a user, or other portion of the user's body wherein use of the device will not impair normal functions of that body portion, it is desired that a means may be provided whereby continued use may be carried out whether activity is sedentary or mobile. It is not known to the inventor of the present invention that any such device exists or has been patented.
Other devices have been produced for warming selected portions of the human body. Typical of the art are those devices disclosed in the following U.S. Patents:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 1,006,415 A. C. Stubling, et al. Oct 17, 1911 1,355,382 A. Blume Oct 12, 1920 2,277,772 L. Marick Mar 31, 1942 2,298,298 M. F. Joy, et al. Oct 13, 1942 2,298,299 M. F. Joy, et al. Oct 13, 1942 2,579,383 F. K. Goudsmit Dec 12, 1951 2,675,798 P. F. Rosmarin Apr 20, 1954 2,697,775 E. H. Licht Dec 21, 1954 2,769,892 D. F. Collins Nov 6, 1956 2,792,827 M. M. Gravin, et al. May 21, 1957 3,249,108 L. A. Terman May 3, 1966 3,953,856 W. M. Loftin Feb 3, 1976 4,023,282 F. Ziegelheafer May 17, 1977 4,042,803 E. P. Bickford Aug 16, 1977 4,094,080 J. J. Sanders Jun 13, 1978 4,249,319 Y. Yoshida Feb 10, 1981 4,373,274 W. J. Michalski Feb 15, 1983 4,455,764 H. E. Rock, et al. Jun 26, 1984 4,495,659 H. Madnick, et al. Jan 29, 1985 4,841,646 L. P. Maurer, Jr. Jun 27, 1989 4,949,887 W. A. Holmes Aug 21, 1990 ______________________________________
Of these devices, only those disclosed by Loftin ('856), Ziegelheafer ('282), Maurer, Jr. ('646), Yoshida ('319), Michalski ('274), Sanders ('080), Rock, et al. ('764), and Holmes ('887) are designed to receive a removable heating source and for heating at least a portion of a wearer's foot. Only the Gravin, et al. ('827), Rosmarin ('798) and Holmes ('887) devices disclose a means for receiving a removable heating source for selectively heating a hand of a wearer. Therefore, only one of the devices disclosed in the above-referenced patents, Holmes ('888), is designed to be used to selectively heat either of the feet or the hands of a wearer. The Holmes device is a multi-use seat cushion which may be use to warm both hands, both feet, the head, a quantity of food, or a seat when used as a seat cushion.
Further, those patents related to the heating of a portion of the wearer's foot do not disclose a device wherein the heat source is disposed proximate the sympathetic center of the foot. Specifically, the heat source is described as being positioned above the toes or at some other location such as under the foot ('319) or at the sides of the foot ('080). The '282 device is also described as being adhered to the boot or shoe of the wearer so as to not be selectively removable from the foot of the wearer without removal of the shoe or boot to which the device is adhered.
None of the prior art devices known to the inventor of the present invention discloses a device wherein a volume is defined for receiving a portion of the wearer's hand or foot, that portion including one of the body's sympathetic centers, wherein the volume is also dimensioned to retain warmed air to prevent loss of heat from the body through that sympathetic center, and wherein the construction includes a heat source receptacle disposed proximate the sympathetic center to be covered. Further, none of the prior art devices known to the present inventor discloses a construction which may be alternately used between the hands and the feet, and specifically to cover at least the upper portion of the top of the user's foot or the back of the user's hand, wherein the construction of the device does not require alteration thereof to move from a hand to a foot, and vice versa.
Therefore, it is an object of this invention to provide a means for warming selected body portions proximate the sympathetic centers--or natural thermostats--of a person during sedentary activity while exposed to cold weather.
Another object of the present invention is to provide a means for maintaining the body temperature generated at the hands and feet of a user.
It is also an object of the present invention to provide such a warming device that may be used to warm other parts of a person's body during any activity while exposed to cold weather.
Another object of the present invention is to provide such a heating device wherein a heat source may be incorporated, the heat source meeting safety standards in order to prevent accidental burns.
Still another object of the present invention is to provide a heating device wherein the heat source may be removed and replaced, thus further providing for the safe cleaning of the warming device.
Yet another object of the present invention is to provide a means for containing a heat source, the means being selectively engageable by one of a person's hands or feet in a manner such that the heat source is positioned proximate one the person's sympathetic centers in order to heat the air surrounding the selected thermostat to prevent the loss of body heat through that center.